Engine air intake systems for work vehicles frequently include a pre-cleaner to remove dirt particles from the intake air prior to the air filter. Many pre-cleaners require a vacuum to pull or “scavenge” dirt particles from the fresh air ingested into the air intake system. Exhaust system aspirators have been used to supply the required vacuum. An exhaust system aspirator, however, creates a restriction in the engine exhaust, raises noise levels and raises the cost of the muffler and/or exhaust pipe. Also, a check valve is needed to prevent back flow of high temperature gases into the pre-cleaner and high temperature hoses must be used.
An alternative approach is to use a fan shroud aspirator as a source of vacuum to a pre-cleaner. This aspirator is typically an opening in the fan shroud linked to the pre-cleaner by a hose. For cost and space savings, it is desirable to reduce the number of extraneous parts required for pre-cleaner aspiration. Modern agricultural tractors and other work vehicles sometimes require a rather long fan shroud to fill the gap between the cooling module and the fan. Thus it is desired to integrate the pre-cleaner aspirator into the fan shroud itself to reduce parts counts and costs and also to satisfy space constraints.